Product Introduction of Liquid Cylinder Assembly
The hydraulic cylinder assembly is one of the core pressure-bearing assemblies at the hydraulic end of the drilling mud pump. It is mainly used to form the working space and internal flow channels for the suction, pressurization and discharge of drilling fluid, and at the same time provides an installation foundation for the cylinder liner, piston working chamber, suction valve, discharge valve, cylinder head, valve cover and related sealing and positioning parts.
When the mud pump is in operation, the power end drives the piston rod and piston to reciprocate through the crosshead, the middle pull rod or the corresponding transmission connection structure. The piston changes the volume of the working chamber inside the cylinder liner. The suction valve and discharge valve inside the liquid cylinder assembly open and close periodically according to the pressure difference, thereby completing the suction and high-pressure discharge of the drilling fluid.
The hydraulic cylinder assembly is subject to periodic high-pressure loads, the impact of valve body opening and closing, drilling fluid erosion, and equipment vibration for a long time. The internal flow channels, valve seat installation holes, cylinder liner installation positions, and pressure-bearing interfaces of the cylinder head and valve cover are all important structural parts. The model of the liquid cylinder must be correctly matched with the model of the mud pump, the specification of the cylinder liner, the specification of the valve group and the connection dimensions.
The main function of the hydraulic cylinder assembly
1. Form the hydraulic end working chamber: The interior of the hydraulic cylinder, together with the cylinder liner, piston and related sealing structures, forms the working chamber of the mud pump, providing the necessary pressure-bearing space for the suction and pressurization of drilling fluid.
2. Form suction and discharge channels: Inside the liquid cylinder, flow channels connected to the suction valve chamber and the discharge valve chamber are set up, allowing the drilling fluid to enter the working chamber along the prescribed path and be discharged from the discharge end.
3. Installation of the suction valve and discharge valve: The liquid cylinder provides an installation and positioning foundation for the valve seat, valve body, valve spring, valve stem guide and related supporting parts, maintaining the correct working relationship between the valve group and the internal flow passage.
4. Installation of the cylinder liner system: The liquid cylinder, the wear-resistant disc, the cylinder liner sealing ring, the cylinder liner flange, the cylinder liner gland and the cylinder liner, etc. form the corresponding cylinder liner installation system to maintain the position and sealing relationship of the cylinder liner.
5. Forming the pressure-bearing boundary at the hydraulic end: The cylinder body, cylinder head, valve cover and their sealing structure jointly seal the high-pressure working medium inside, which is one of the main pressure-bearing structures at the hydraulic end of the slurry pump.
The suction and discharge working process
During the suction stroke, the movement of the piston increases the volume of the working chamber and forms a corresponding pressure difference. The suction valve opens, and the drilling fluid enters the internal flow channel of the cylinder through the suction main pipe and the suction interface, and then enters the working chamber through the suction valve.
During the discharge stroke, the reverse movement of the piston reduces the volume of the working chamber and increases the pressure of the working medium. When the suction valve is closed, the discharge valve opens under the action of pressure difference, and the high-pressure drilling fluid enters the main discharge pipe or the corresponding high-pressure discharge system through the discharge channel of the liquid cylinder.
The structure of the internal flow channels of the liquid cylinder is directly related to the passage paths of the suction and discharge media. During maintenance, attention should be paid to the turning areas of the flow passage, the vicinity of the valve seat, and other locations that may be eroded by high-speed drilling fluid.
Installation structure of the valve cavity and valve seat
The liquid cylinder is equipped with the corresponding valve cavities and valve seat installation positions for the suction valve and the discharge valve inside. The valve seat needs to maintain the correct center and load-bearing relationship within the specified installation holes of the liquid cylinder, while the valve body is periodically opened and closed in coordination with parts such as the valve stem guide and the valve spring.
The valve seat installation hole and its mating surface are important inspection positions for the liquid cylinder. If erosion, corrosion, scratches, deformation or abnormal fit occurs, it may affect the positioning of the valve seat and the working condition of the valve group.
When replacing the valve seat, the operation should be carried out in accordance with the corresponding slurry pump maintenance process. Incorrect disassembly and assembly methods that may damage the installation hole of the liquid cylinder valve seat should not be adopted.
Cylinder liner installation system
The hydraulic cylinder assembly and the cylinder liner system have a direct positioning and sealing relationship. According to the specific structure of the mud pump, the installation area of the cylinder liner can be coordinated with wear-resistant discs, cylinder liner sealing rings, cylinder liner flanges, cylinder liner gland covers and cylinder liners and other parts.
The cylinder liner needs to maintain the correct center position to enable the piston to move back and forth stably inside the cylinder liner. If abnormal wear occurs on the relevant positioning surfaces of the liquid cylinder, the installation position of the wear-resistant disc or the installation reference of the cylinder liner, it may lead to abnormal positioning of the cylinder liner and increase the risk of uneven wear between the piston and the cylinder liner.
When leakage occurs repeatedly at the cylinder liner installation interface, in addition to checking the cylinder liner sealing ring, the status of the corresponding sealing and positioning areas of the liquid cylinder, the wear-resistant disc, and the cylinder liner clamping structure should also be inspected.
Cylinder head and valve cover installation interface
The hydraulic cylinder is usually set with a pressure-bearing opening for the installation of the cylinder head and valve cover. The cylinder head is used to close the relevant end openings of the working chamber, while the valve cover is used to close the maintenance valve chamber corresponding to the suction valve or discharge valve.
The cylinder head sealing ring and the valve cover sealing ring respectively form static seals with the corresponding sealing cavities of the liquid cylinder. Therefore, the surface conditions of the sealing holes, positioning steps and sealing cavities on the liquid cylinder will directly affect the reliability of these static sealing positions.
If leakage persists at the cylinder head or valve cover position, in addition to replacing the sealing parts, it is also necessary to check whether there is erosion, corrosion, scratches, deformation or other damage that affects the seal in the hydraulic cylinder sealing cavity.
The supply scope of the hydraulic cylinder assembly
The supply scope of "hydraulic cylinder assemblies" may vary among different manufacturers and in different procurement projects. Some products take the liquid cylinder body as the core and are pre-installed with some positioning, sealing or connecting parts. Some other items may further include valve groups, valve covers, cylinder heads, cylinder liner related parts or other accessories.
Therefore, when purchasing a hydraulic cylinder assembly, one should not merely rely on the name of the "assembly" to determine the actual parts included. It is recommended to clearly determine whether the liquid cylinder body, valve groups, seals, covers, fasteners, etc. are included based on the BOM list, original part numbers, assembly drawings or the supply scope confirmed by both parties.
The difference between the hydraulic cylinder assembly and the hydraulic end assembly
Hydraulic cylinder assembly: Centered on the pressure-bearing body of the hydraulic cylinder, it mainly includes the internal working chamber, valve chamber, flow channel and related installation interfaces of the hydraulic cylinder. The specific range of accessories is determined according to the supply definition.
Hydraulic end assembly: It is usually a more complete concept of hydraulic end functional assembly, which may involve hydraulic cylinders, valve groups, cylinder liner systems, piston or plunger related systems, suction and discharge interfaces, and other matching parts. The actual boundaries also need to be confirmed according to the specific pump type and BOM.
Therefore, when inquiring about prices and making purchases, it should be clear whether what is needed is a single hydraulic cylinder body, a hydraulic cylinder assembly with accessories, or a more complete hydraulic end assembly.
Common injuries and examinations
The hydraulic cylinder is subject to periodic high pressure and drilling fluid erosion for a long time. During maintenance, the internal flow channels, valve seat installation holes, cylinder liner installation areas, cylinder head holes, valve cover holes, sealing cavities, suction and discharge interfaces, as well as external installation and load-bearing parts should be inspected with emphasis.
Common abnormalities include flow channel erosion, corrosion, damage to the sealing surface, wear at the valve seat installation position, damage to the thread or installation hole, and abnormal cracks in the pressure-bearing area, etc.
When suspected cracks, severe erosion or other pressure-bearing structural damage are found in the liquid cylinder body, inspection and assessment should be carried out in accordance with the corresponding equipment manufacturer and maintenance specifications. It is not allowed to continue using it or repair the pressure-bearing parts at will without technical basis.
Key points for selection
When purchasing the drilling mud pump cylinder assembly, it is recommended to focus on confirming the following information:
1. Brand, series and specific model of mud pump;
2. Model and original part number of the liquid cylinder assembly;
3. Left, middle, right or other installation positions, if there is a position distinction for the corresponding pump type;
4. Cylinder liner specifications and cylinder liner installation dimensions;
5. Specifications for pistons and piston rods;
6. Specifications of the suction valve and discharge valve;
7. Valve seat shape and installation dimensions;
8. Specifications of valve cover and cylinder head;
9. Sealing structure of valve cover and cylinder head;
10. Suction interface size and connection form;
11. Interface size and connection form for discharge;
12. Installation and connection dimensions of the liquid cylinder and the pump body;
13. Dimensions of tie rods or related connection structures;
14. Work pressure level;
15. Material and heat treatment requirements for the liquid cylinder body;
16. Internal flow channel and installation hole structure of the liquid cylinder;
17. Specific BOM and supply scope of the hydraulic cylinder assembly;
18. Original assembly drawings, physical samples or technical drawings.
Installation and Maintenance
Before disassembling and assembling the hydraulic cylinder assembly, it is necessary to confirm that the mud pump has been shut down, the suction and high-pressure discharge systems have been isolated, and the internal pressure at the hydraulic end has been completely released. The liquid cylinder is a major pressure-bearing component. Its disassembly and assembly should be carried out in accordance with the corresponding maintenance procedures for the mud pump.
Before installation, the installation surface, positioning surface and connection position of the liquid cylinder and the pump body should be inspected. Mud, corrosive substances, metal shavings and burrs should be removed. At the same time, the condition of the tie rods, studs and related connecting parts should be checked.
When installing parts such as valve seats, valve groups, cylinder liners, cylinder heads and valve covers, their installation holes, positioning surfaces and sealing cavities should be inspected respectively to prevent assembly damage caused by foreign objects, burrs or part skew.
The connection requirements between the liquid cylinder and the pump body as well as the fastening requirements of each pressure-bearing cover should be carried out in accordance with the regulations of the corresponding mud pump manufacturer. The general tightening torque should not be used in isolation from the specific thread specification, fastener grade and assembly process.
Procurement Instructions
Juli Petroleum Drilling and Production Equipment Co., Ltd. provides hydraulic cylinder assemblies and hydraulic end accessories for drilling mud pumps. The liquid cylinder assembly can be selected based on the model of the mud pump, the original part number of the liquid cylinder, the specification of the cylinder liner, the specification of the valve group, the structure of the cylinder head and valve cover, the suction and discharge interfaces, the installation dimensions, the pressure rating and the technical drawings.
When placing an order, it is recommended to clearly specify the supply scope of the hydraulic cylinder assembly at the same time, including whether it includes suction valve and discharge valve assemblies, valve stem guides, valve springs, valve covers, cylinder heads, seals, cylinder liner mounting parts and other accessories. The BOM or the configuration list confirmed by both parties shall be used as the basis for supply.